function bgArg() {}
bgArg.prototype.begin = function() {
	//this.angle = 0;
	this.x = can.width/2;
	this.y = 10;
	this.R1 = 50;//Math.random() * 10;
	this.R2 = Math.random() * 100 + 500;

	this.r1 = 17 / 256;
	this.g1 = 143 / 256;
	this.b1 = 166 / 256;

	this.r2 = 9 / 256;
	this.g2 = 48 / 256;
	this.b2 = 103 / 256;
}
bgArg.prototype.drawBackGround = function() {
	this.col1 = rgbColor(this.r1, this.g1, this.b1);
	this.col2 = rgbColor(this.r2, this.g2, this.b2);

	//this.x = 300 * Math.cos(this.angle) + can.width / 2;

	var grd = ctx2.createRadialGradient(this.x, this.y, this.R1, this.x, this.y, this.R2); //在画布上确定两个渐变的圆心和半径
	grd.addColorStop(0.001, this.col1); //内部渐变颜色和从哪里开始渐变
	grd.addColorStop(0.999, this.col2); //外部渐变颜色和渐变到哪里为止
	ctx2.fillStyle = grd;
	ctx2.fillRect(0, 0, can.width, can.height);

	
	/*this.angle += 0.005;

	if (this.angle > Math.PI * 2) {
		this.angle = 0;
	}*/
}



function drawBG() {
	backG.drawBackGround();

	setTimeout(drawBG, 60);
}
